1. Field of the Invention
The present invention relates to communications network in general and, in particular, to systems for interconnecting electrical sub-systems such as modules, ASIC, etc.
2. Prior Art
The proliferation of computers and related electrical machines, such as routers, switches, servers, etc., have created a need for improved interconnection devices and methods. The need is present not only at the box level, but also at the sub-assembly level. The box level relates to interconnecting standalone boxes, such as workstations, personal computers, servers, routers, etc., whereas the sub-assembly level relates to components such as ASICS, modules, etc., within the boxes.
Traditionally two interconnecting approaches or techniques have been used. In one technique, a bus structure does the interconnection. Even though the bus structure transfers data relatively fast, it is expensive and requires multiple pins (one for each bit) at the interface. There are many designs in which pin counts and cost are very sensitive issues. As a consequence, bus structures are not suitable for interconnecting sub-assemblies.
In the other approach, serial links are used as the interconnecting mechanism. Even though the serial links solve some of the problems associated with the bus structures, they too have shortcomings which limit their use. Probably, the most severe of all the shortcomings is that the serial links are relatively low speed. For example, an RS232 serial link transmits data at approximately 115K bits/sec. Surely, this speed makes them unsuitable for use in high speed, say 500 and greater Mbps, applications.
The prior art has provided serial link devices with speed greater than RS232, albeit less than 500 Mbps. Even though these systems point in the right direction, they suffer several defects including unnecessary use of pins to transmit clock signal, etc.
Examples of the prior art systems are set forth in the following U.S. patents:
U.S. Pat. No. 5,081,654 PA1 U.S. Pat. No. 5,651,033 PA1 U.S. Pat. No. 5,533,072 PA1 U.S. Pat. No. 5,587,709 PA1 U.S. Pat. No. 5,675,584 PA1 U.S. Pat. No. 5,714,904
In view of the above, there is a need for a more efficient high speed interconnection system.